Why Thai? Why not, when it's great; Restaurant: The owner may have trained as a sushi chef, but Thai One On serves up some of the most authentic Thai food around.

Elizabeth LargeTHE BALTIMORE SUN

Vanhdy Sesum's father is Chinese, and he himself has trained long years as a sushi chef. So you could reasonably wonder why he opened a Thai restaurant a couple of months ago. And not only that. He opened what may be the best Thai restaurant in the area.

To be fair, Sesum's mother is Thai. But still, the 31-year-old's other two restaurants are Japanese: San Sushi in Cockeysville and San Sushi Too next door to Thai One On.

"Sushi does very well around here, but Japanese food isn't really strong," Sesum explains. By that he means the San Sushi Too kitchen, as opposed to the sushi bar, wasn't getting much use. When he learned that a chef from Thai Landing was looking for a new job, Sesum suggested he use the kitchen space to produce dishes for a new restaurant adjoining the Japanese dining room.

The Thai dining room doesn't look like much, although it's clean, fresh and comfortable. In spite of the separate signs outside, Thai One On and San Sushi aren't really separate. They have the same kitchen and connecting doors, and you can get either kind of food in either dining room. In fact, the Thai One On tables are set with chopsticks, although Thai food is eaten with a fork and spoon.

Seeing those chopsticks, who would suspect that here you'll get some of the most authentic Thai food around? Not that authenticity is always a plus. I'm so used to the substitution of sweet red peppers for fresh red chili peppers in Thai cucumber salad that I popped the red slivers in without thinking. Misery. Rule No. 1 for eating at Thai One On (unless you have a stronger constitution than I do): Inspect anything red carefully.

There are so many good things here it's hard to know what to recommend first. Most spectacular is the whole fried fish with three sauces and crispy basil. The evening we were there it was a beautifully fresh whole flounder. When I say that there was only one sauce and no crispy basil and we still couldn't have been happier with the dish, you'll understand how good it was.

First of all, Thai One On's food is technicolor-bright: emerald-green peas, snow peas and beans; vibrant-orange carrots; blood-red tomatoes and, yes, chilies. Each dish, sprinkled with jade-green leaves of coriander or basil, is prettier than the last.

In almost every dish you can taste quite distinct levels of salty, sweet, spicy and sour, with fresh herbs and peppers adding explosive flavor.

The whole fried flounder, boasting tender white flesh, was covered with colorful vegetables, mushrooms and a delicately flavorful sauce. Spectacular, even though I don't usually like sauces that are even faintly sweet with fish.

If you want something more usual, you won't find a better pad thai than Thai One On's. Large, perfect shrimp are nestled in the delicious stir-fry of rice noodles, bean sprouts, egg and ground peanuts.

If you're feeling a bit more adventuresome, try the sliced roasted duck in a dreamy red curry sauce (made with dried red chilies) with pineapple chunks, string beans and tomatoes.

A first course of plump mussels in a little earthenware casserole dish was attractively arranged with lemongrass and coriander. Lime added zing to their broth. But our favorite appetizer was slices of high- quality, tender, rare beef on lettuce leaves tossed with spices and lime juice.

Thai One On has green tea and red bean ice cream for dessert, but I would pass on those Japanese-inspired desserts any day for the classic Thai sticky rice -- sweet and, yes, appealingly sticky. You can get it topped with slivers of egg custard, an odd combination that somehow works. But then you wouldn't have the sticky rice with its perfect foil: the juicy tart-sweetness of sliced mango.

THAI ONE ON

Food: ****

Service: **

Atmosphere: **1/2

Where: 10 W. Pennsylvania Ave., Towson

Hours: Open Monday through Saturday for lunch and dinner, Sunday dinner only